Paper coating lattices, such as styrene-butadiene emulsion polymers, are typically added to bind inorganic pigments together in order to make a paper surface smooth and uniform for printing. Coating printing strength, gloss, blister resistance, smoothness, print gloss and print mottle are all key characteristics of coated paper and can be impacted by the latex composition. Prior attempts to improve one of these characteristics have generally resulted in compromising other characteristics. In accordance to conventional offset printing wisdom, for instance, increasing the latex average particle size decreases printing strength of a coated paper, while it improves its glossability.
U.S. Pat. No. 5,420,190 teaches a paper coating composition for use in gravure printing. Data is provided to illustrate that the average particle size of the latex should be limited. For styrene butadiene latex having an average particle size of greater than 200 nanometers, high shear viscosity resulted in deterioration in rotogravure print quality of coated paper prepared with the composition.
There is a need for a latex composition that provides a novel balance of properties, maximizing as many of the above required properties as possible.